DAY3SVR: Nws Storm Prediction Center Norman Ok

ACUS03 KWNS 280726
SWODY3
SPC AC 280725

DAY 3 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0225 AM CDT THU JUN 28 2012

VALID 301200Z - 011200Z

...NRN AND CNTRL PLAINS...
AN UPPER-LEVEL RIDGE IS FORECAST TO MOVE INTO THE NRN HIGH PLAINS ON
SATURDAY WITH WEST TO NORTHWEST FLOW LOCATED ACROSS THE NRN PLAINS
EXTENDING SEWD INTO THE UPPER MS VALLEY. SEVERAL MODELS SUGGEST A
SUBTLE SHORTWAVE TROUGH WILL MOVE ESEWD ACROSS THE NRN PLAINS DURING
THE AFTERNOON. THIS ALONG WITH STRONG INSTABILITY LOCATED FROM
ECNTRL NEB NWD INTO THE ERN DAKOTAS AND MODERATE DEEP LAYER SHEAR
SHOULD BE SUFFICIENT FOR A SEVERE THREAT. HOWEVER...UNCERTAINTY
EXISTS CONCERNING WHERE THUNDERSTORMS ARE MOST LIKELY TO DEVELOP
SATURDAY AFTERNOON. THE GFS DEVELOPS STORMS IN ERN ND AND NW MN
DURING THE AFTERNOON. HOWEVER...THE MODELS APPEAR TO BE IN AGREEMENT
THAT A STORM COMPLEX WILL DEVELOP FURTHER TO THE SOUTH IN SRN SD AND
NRN NEB DURING THE EVENING. THE SRN AREA WOULD BE CONDITIONAL DUE TO
THE WARM AIR AT MID-LEVELS AND LACK OF LARGE-SCALE ASCENT.
CONSIDERED ADDING A SLIGHT RISK IN PARTS OF THE NRN AND CNTRL PLAINS
BUT WILL WAIT FOR ADDITIONAL MODEL RUNS TO HELP BETTER DEFINE THE
SCENARIO.

...SRN GREAT LAKES/UPPER OH VALLEY...
WEST TO NORTHWEST FLOW WILL BE IN PLACE SATURDAY FROM THE UPPER MS
VALLEY ESEWD INTO THE NERN STATES WITH A LOW-AMPLITUDE UPPER-LEVEL
TROUGH LOCATED IN THE OH VALLEY. AT THE SFC...A QUASI-STATIONARY
FRONTAL BOUNDARY IS FORECAST TO BE LOCATED FROM NEAR CHICAGO
EXTENDING EWD TO AROUND LAKE ERIE. SCATTERED THUNDERSTORM INITIATION
WILL BE POSSIBLE ALONG THE BOUNDARY SATURDAY AFTERNOON AS SFC TEMPS
WARM AND MODERATE INSTABILITY DEVELOPS FROM THE BOUNDARY SWD.
ALTHOUGH THE MODELS DISAGREE ON WHERE THE GREATEST CONVECTIVE
COVERAGE WILL BE...THE GFS AND NAMKF SUGGEST STORMS WILL DEVELOP IN
LOWER MI AND SPREAD SEWD INTO THE UPPER OH VALLEY. NAMKF FORECAST
SOUNDINGS ALONG THIS CORRIDOR AT 21Z/SAT SHOW MLCAPE VALUES OF 2500
TO 3500 J/KG WITH 0-6 KM SHEAR AROUND 40 KT AND UNIDIRECTIONAL WIND
PROFILES. THIS ENVIRONMENT SHOULD SUPPORT SEVERE THUNDERSTORMS
CAPABLE OF PRODUCING STRONG WIND GUSTS. HOWEVER...ANY SEVERE THREAT
WILL BE CONDITIONAL UPON WHERE THE STORMS CAN INITIATE. AT THIS
POINT WILL LEAVE THE AREA SEE TEXT DUE TO UNCERTAINTY.

..BROYLES.. 06/28/2012

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